Flask



FIG. 1 is a perspective view of a flask showing our new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a left side elevation view thereof;

FIG. 5 is a right side elevation view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines depict features of the flask that form no part of the claimed design. 

CLAIM We claim the ornamental design for a flask, as shown and described. 